i got the 2 resistors ordered. would it be safe to solder the diodes back in or should i leave them out for further testing?
Yes.
Remember to clamp all transistors tightly to the sink and to have a 10 amp fuse in the B+ line before applying power.
Remember to clamp all transistors tightly to the sink and to have a 10 amp fuse in the B+ line before applying power.
i replaced the 2 resistors and clamped the board in the sink. now with no load the wave looks perfect until i make it clip, then it looks funny. do i now need to reinstall the 2 diodes?
Yes. Install 1 then check the signal. If it remains good, reinstall the second one and recheck it.
Lift the other 2 transistors, one at a time (starting with Q218). To see if the distortion is eliminated.
Are you sure that the emitter resistor you installed is a 0,1 ohm resistor?
Are you sure that the emitter resistor you installed is a 0,1 ohm resistor?
yep it's a .1 ohm. tried both Q217, Q218 seperately. and i still got the noise. when the q218 was out it made the other channel look wierd now with it back in it looks normal (if that matters).
sorry i dont have pics, my phone is dead.
sorry i dont have pics, my phone is dead.
Charge your phone so that you can post photos.
Are you driving the amp with a pure sine wave or with music?
Are you driving the amp with a pure sine wave or with music?
You need to check all of the components in that part of the protection circuit. Check the rest of the resistors in the image below. Also make absolutely sure that you don't have any broken/cracked traces or bad solder connections on the components you replaced. You may need a lighted magnifying glass to see bad/broken connections.
Attachments
FIRST IS THE LEFT CHANNEL BEFORE DISTORTION.
SECOND IS THE LEFT CHANNEL TURNED ALL THE WAY UP.
THIRD IS THE RIGHT CHANNEL TURNED ALL THE WAY UP.
BOTH ARE NEARLY IDENTICAL BEFORE CLIPPING.
THAT'S A 60HZ WAVE. NO LOAD.
SECOND IS THE LEFT CHANNEL TURNED ALL THE WAY UP.
THIRD IS THE RIGHT CHANNEL TURNED ALL THE WAY UP.
BOTH ARE NEARLY IDENTICAL BEFORE CLIPPING.
THAT'S A 60HZ WAVE. NO LOAD.
Attachments
Did you check the resistors and the connections?
With the protection circuit disabled (diodes removed) do both channels clip the same?
With the protection circuit disabled (diodes removed) do both channels clip the same?
WITH D204 & D205 BOTH REMOVED IT DOES THE SAME. ALL THE CONNECTIONS AND TRACES APPEAR TO BE OKAY. I AM CURRENTLY CHECKING THE RESISTORS.
Didn't you state that the amp produced a clean signal with the protection circuit defeated (transistors or diodes removed)?
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